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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef ASH_ACCELERATOR_KEY_HOLD_DETECTOR_H_
#define ASH_ACCELERATOR_KEY_HOLD_DETECTOR_H_
#include "ash/ash_export.h"
#include "base/memory/scoped_ptr.h"
#include "ui/events/event_handler.h"
namespace ui {
class KeyEvent;
}
namespace ash {
// This class is used to implement action when a user press and hold the key.
// When a user just pressed and released a key, normal pressed event gets
// generated upon release.
class ASH_EXPORT KeyHoldDetector : public ui::EventHandler {
public:
class Delegate {
public:
virtual ~Delegate() {}
// If this return false, the event handler does not process
// the event at all.
virtual bool ShouldProcessEvent(const ui::KeyEvent* event) const = 0;
// This should return true if the event should start the state transition.
virtual bool IsStartEvent(const ui::KeyEvent* event) const = 0;
// Called when the key is held.
virtual void OnKeyHold(const ui::KeyEvent* event) = 0;
// Called when the key is release after hold.
virtual void OnKeyUnhold(const ui::KeyEvent* event) = 0;
};
explicit KeyHoldDetector(scoped_ptr<Delegate> delegate);
~KeyHoldDetector() override;
// ui::EventHandler overrides:
void OnKeyEvent(ui::KeyEvent* key_event) override;
private:
// A state to keep track of one click and click and hold operation.
//
// One click:
// INITIAL --(first press)--> PRESSED --(release)--> INITIAL[SEND PRESS]
//
// Click and hold:
// INITIAL --(first press)--> PRESSED --(press)-->
// HOLD[OnKeyHold] --(press)--> HOLD[OnKeyHold] --(release)-->
// INITIAL[OnKeyUnhold]
enum State {
INITIAL,
PRESSED,
HOLD
};
State state_;
scoped_ptr<Delegate> delegate_;
DISALLOW_COPY_AND_ASSIGN(KeyHoldDetector);
};
} // namespace ash
#endif // ASH_ACCELERATOR_KEY_HOLD_DETECTOR_H_
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